Two-step alarm disarming device with automatic rearming feature

Abstract

The invention is a two-step alarm disarming device with automatic rearming which uses sensors and buffer circuits to detect the condition of the car doors, hood, and trunk. It can disarm an alarm in two steps--with a signal input to an exterior key switch buffer for temporary disarming and a signal input to the ignition for permanent disarming. It is comprised of two-step alarm disarming circuits, a flip-flop, a timer, and a buffer for alarm disarming so that the burglar alarm can operate at maximum effectiveness without failure due to external interference or user negligence.

I claim: 
     
       1. An automotive vehicle burglar alarm system for an automotive vehicle having a vehicle door and an ignition system, alarm means to sound an alarm in response to the opening of a door of said vehicle when said alarm means is armed and allowing said door to be opened without sounding said alarm when said alarm means is disarmed, an external key switch buffer circuit selectively operable from outside the vehicle to generate an initial disarming signal, and two-step disarming circuit means to disarm said alarm means in response to receiving said initial disarming signal as a first step and the activation of said vehicle ignition system as a second step within a predetermined time interval after receiving said initial disarming signal, said two-step disarming circuit means temporarily disarming said alarm means during said predetermined interval and automatically rearming said alarm means at the end of said predetermined time interval if said ignition system is not activated during said predetermined time interval. 
     
     
       2. A vehicle burglar alarm system as recited in claim 1, wherein said external key buffer circuit means is selectively operable to generate said initial disarming signal in response to a radio transmitted signal.